Abstract

Summary Since its definition at the council of Nicea the date of Easter had been calculated on a cyclical basis. The Easter formula publicized by C. F. Gauss in 1800 has neither achieved recognition with the chronologists nor with the officials of the papal curia, responsible for the fixing of Easter. In the paper being presented here the elements of medieval computus are transformed on an arithmetical basis and from this a formula for the fixing of Easter is developed. With the help of these two components it is possible to calculate the Julian as well as the Gregorian dates of Easter and, in addition the calendar of any given year. The formula for the date of Easter being submitted here can be traced back exclusively to the elements of the medieval computus and can be ratified by the chronologists. Thus it renders possible the fixing of every Easter date with the help of a pocket calculator or the use of two small tables. This demonstrates that the history of methodology contains tools in order to develop a ‘new’ solution of a systematical problem